Node, apparatus, system and method regarding a frame support for solar mirrors

ABSTRACT

A node for a solar frame including an elongate portion having a channel extending through it in which a structural element is disposed or a solid elongate portion on to which a structural element is disposed. The node comprises a fin extending radially outward from the elongate portion where at least 5% of the volume of the fin is replaced by at least a single void extending essentially in parallel with the channel or the extrusion direction of the solid elongate portion. An apparatus for transmitting torque in a solar frame having structural elements and a support. A system for solar mirrors. A node for a solar frame. A method for connecting a structural element with a strut having a strut end piece of a solar mirror support frame. A method for producing a node for solar mirror frame.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/858,717 filed Sep. 18, 2015, now U.S. Pat. No. 10,240,819, which is adivisional of U.S. patent application Ser. No. 14/133,150 filed Dec. 18,2013, now U.S. Pat. No. 9,140,282 issued Sep. 22, 2015, which is adivisional of U.S. patent application Ser. No. 13/135,137 filed Jun. 27,2011, now U.S. Pat. No. 8,627,632 issued Jan. 14, 2014, which is acontinuation-in-part of U.S. patent application Ser. No. 12/927,812filed Nov. 24, 2010 and is a continuation-in-part of U.S. patentapplication Ser. No. 12/798,757 filed Apr. 10, 2010, and is acontinuation-in-part of U.S. patent application Ser. No. 12/587,043,filed Sep. 1, 2009, all of which are continuations-in-part of, and whichthis application is a continuation-in-part of U.S. patent applicationSer. No. 12/583,787 filed Aug. 26, 2009, which claims the benefit fromU.S. provisional application Ser. No. 61/190,573 filed Aug. 29, 2008,all of which are incorporated by reference herein.

FIELD OF THE INVENTION

The present invention pertains to a frame support for solar mirrors. (Asused herein, references to the “present invention” or “invention” relateto exemplary embodiments and not necessarily to every embodimentencompassed by the appended claims.) More specifically, the presentinvention pertains to various components of a frame support for solarmirrors.

BACKGROUND OF THE INVENTION

This section is intended to introduce the reader to various aspects ofthe art that may be related to various aspects of the present invention.The following discussion is intended to provide information tofacilitate a better understanding of the present invention. Accordingly,it should be understood that statements in the following discussion areto be read in this light, and not as admissions of prior art.

The inventors have developed several geometries to provide support ofparabolic mirrors—for the sake of explanation, these are called “SeriesThree” and “Series Five” (with the Series Three 60 having three maintriangles as viewed from the end and Series Five 62 having five maintriangles as viewed from the end.) See FIGS. 16A and 16B.

Reducing frame weight will generally lead to more cost effective frames.Increasing frame rigidity (reducing deflections) will improve slopeerror and lead to a frame which converts a higher % of the solar energyhitting the mirrors into usable heat content/improved efficiency of theentire solar field which improves the return on investment for the solarfield.

The prior WES patent applications and figures are similar to FIGS. 16Aand 16B (showing Series 3 and Series 5). The Series 5 design shown inFIG. 16A is an alternate “geometry”. Since that time, furtherdevelopment has focused on more of a traditional space frame designwhere all of the struts come in to a common “unified hub” 64 (in FIG. 65, one can see how every other “hub” uses different struts). With the WESStrut End Piece and Sleeve designs, the member (struts)/forces can bebrought together into very small physical spaces. Bringing all of theforces into a unified hub 64 reduces essentially any bending moments,improving the efficiency of the space frame in terms of load carryingcapacity and deflection. When the WES Series 5 62 was redesigned to usea unified hub 64 configuration, there were improvements in bothdeflection and individual member loads, as the bending moments wererelatively low due to short strut lengths and short connections betweenthe sleeves along the chord.

FIG. 17 depicts named components of the prior patent. application Series5 multifinned sleeve and strut end piece design—useful to refer to re:nomenclature of the rest of this patent application. Note that thisfigure also shows the multiple parallel fins 70 of the sleeve 68, whichreceives a main support member 66, and/or strut end piece (redesigned asnon-parallel “guided insertion” in subsequent designs). Depending onload characteristics and fasteners, the number of fins on the sleeve 68or strut end piece can be modified; for example, below there isdiscussed the single fin sleeve, with one or more fins on the matingstrut end piece. In the earlier WES patent applications and framedesign, single finned strut end pieces were shown inserted into a dualfin sleeve arrangement.

The parabolic mirror framework supports the weight of itself and thesupported mirrors and the wind and associated torque forces from thewind, which can be substantially higher than the simple weight of theassembled structure. These structures are generally 8, 12 (or other)meters long, supported at each end (or otherwise, as disclosed in theWES Rolling rib patent application) in a manner which allows rotation ofthe entire frame so that the parabolic mirrors follow the sun and focusthe solar radiation optimally. The truss geometry and components aredesigned for each specific application (e.g. 8, 12 or other spanlengths, wind conditions at installation location, drive mechanism andwhether it acts on the solar frames individually or drives one framerotation which in turn drives others (for 2, 3, 4, 5 or more in series,increasing/multiplying the total torque on the driven frame by thenumber of frames that each drive actuates)).

The forces acting on the frame are transmitted through the truss strutsto the truss sleeves (nodes) which form the vertices of the trianglesmade up by the struts. The load capability and efficiency of the trussgeometry and the capabilities of the components (struts, strut endpieces (where used), sleeves, fasteners, etc.) define how efficientlythe truss performs and how optically accurate the collection of solarradiation is (leading to greater energy efficiencies).

FIG. 27A shows an angled strut end piece connecting to a “sleeve” (shownas a tubular shape, but can be a different cross section). The strut endpiece transfers the tensile or compressive loads from the strut whichslips over and is fastened to the strut end piece which then fastens tothe sleeve (node), where various struts and/or strut end piecesconcentrate their loads.

FIG. 27B shows multiple struts and strut end pieces converging theirforces onto the sleeve 68 (through which passes the chord, chordcouplers, segmented chords, chord connector(s), etc. defining the 8, 12(or other) length of the solar frame). The system of struts 32, strutend pieces 30 (where used), sleeves 68 and chords are designed such thatat each vertices of the frame the forces converge on a common point 76(which may or may not be where there is actual physical material fromthe frame materials). This convergence to a common point 76 prevents oddbending moments at the sleeve connection.

BRIEF SUMMARY OF THE INVENTION

The present invention pertains to a node for a solar frame. The nodecomprises an elongate portion which may have a channel extending throughit in which a structural element is attached to or the node may comprisea solid elongate portion onto which structural elements are attached.The node comprises a fin extending radially outward from the elongateportion where at least 5% of the volume of the fin is replaced by atleast a single void extending essentially in parallel with the channel.

The present invention pertains to an apparatus for transmitting torquein a solar frame having structural elements and a support. The apparatuscomprises a torque plate having a first side and a second side. Theapparatus comprises a knob attached to the first side of the plate forengaging the support. The apparatus comprises a plurality of tubesattached to the second side of the plate for receiving structuralelements of the frame.

The present invention pertains to an apparatus for transmitting torquein a solar frame having structural elements and a support. The apparatuscomprises a torque plate having a first side and a second side. Theapparatus comprises a knob which goes through and attaches to both thefirst and second side of the torque plate for engaging the support. Theapparatus comprises a first tube which goes through and attaches to boththe first and second side of the torque plate for receiving structuralelements of the frame. The apparatus comprises a second tube having afirst side and a second side which goes through and attaches to both thefirst and second side of the torque plate. The apparatus comprises aplurality of additional tubes which go through and attach to both thefirst and second side of the torque plate.

The present invention pertains to a system for solar mirrors. The systemcomprises a support. The system comprises a first frame engaged with thesupport on which solar mirrors are disposed. The system comprises asecond frame engaged with the support on which solar mirrors aredisposed. The system comprises rotational means disposed on either sideof each frame for rotating the respective frame. The system comprises afirst force applying means for applying a force to the first frame tomove the first frame. The system comprises a second force applying meansfor applying a force to the second frame to move the second frame.

The present invention pertains to a node for a solar frame. The nodecomprises a solid elongate portion having fastener holes to which astructural element is attached with fasteners to the elongate portion.The node comprises a fin extending outward from the elongate portionwhere at least 5% of the volume of the fin is replaced by at least asingle void 204.

The present invention pertains to a node for a solar frame. The nodecomprises an elongate portion having a channel extending through it inwhich a structural element is disposed or the node may comprise a solidelongate portion onto which structural elements are attached. The nodecomprises a fin extending radially outward from the elongate portionwhere at least 5% of the volume of the fin is replaced by at least asingle void extending essentially in the extrusion direction.

The present invention pertains to a method for connecting a structuralelement with a strut having a strut end piece of a solar mirror supportframe. The method comprises the steps of placing a structural element ina channel of an elongate portion of a node or onto a solid elongateportion of the node. There is the step of attaching the strut end pieceto a fin of the node extending radially outward from the elongateportion where at least 5% of the volume of the fin is replaced by atleast a single void extending essentially in parallel with the channelor in the extrusion direction.

The hollow fin design disclosed enhances the frame system's rigidity andlowers the stresses that the node element is subject to (allowingreduced part weight), while at the same time reducing the circumscribingcircle size required; the tradeoff for this is slightly increasedextrusion difficulty, which can cause slightly slower extrusionvelocities and slightly higher $/lb costs for the profile.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

In the accompanying drawings, the preferred embodiment of the inventionand preferred methods of practicing the invention are illustrated inwhich:

FIG. 1 is a hollow single fin node.

FIG. 2 is a hollow single fin node—Front view.

FIG. 3 is a hollow single fin node complete with all SEP, BEP & struts &beams—Front view.

FIG. 4 is a hollow single fin node with CEP (chord end piece)—ISO view.

FIG. 5 is a hollow single fin node complete with all SEP, CEP, BEP &struts & beams—Front view.

FIG. 6 is a hollow single fin node with CEP (chord end piece) andchord—ISO view.

FIG. 7 is a hollow single fin node with SEP & CEP with strut and chord.

FIG. 8 is a hollow single fin node complete with all SEP, CEP & BEP(beam end piece).—Bottom ISO view.

FIG. 9 is a hollow single fin node complete with all SEP, CEP, BEP &struts, chords, & beams.—Bottom ISO view.

FIG. 10 is a hollow single fin node complete with all SEP, CEP, BEP &struts, chords, & beams—Top ISO view (close up).

FIG. 11 is a hollow single fin node in series 5 frame—Front ISO view.

FIG. 12 is a hollow single fin node in series 5 frame—Side ISO view.

FIG. 13 is a rolling rib location concept—End view.

FIG. 14A is a rolling rib roller assembly—Front view.

FIG. 14B is a rolling rib roller assembly—ISO view.

FIG. 15A is an outside mirror rail and upright connection—End view.

FIG. 15B is an outside mirror rail and upright connection—Side view.

FIG. 15C is an outside mirror rail and upright connection multiple piecemirror rail connection—Side view.

FIG. 15D is a mirror rail upright upper bracket.

FIG. 15E is a mirror rail upright lower bracket.

FIG. 16A shows Series 5 frame—Front view.

FIG. 16B shows Series 3 frame—ISO view.

FIG. 17 shows Series 5 multifinned sleeve and strut end piece design(nomenclature for patent application).

FIG. 18A shows a strut—with support plates.

FIG. 18B shows a small strut—notched.

FIG. 18 c shows a large strut—notched.

FIG. 19 shows a hollow fin node with notched strut attached to singlehollow.

FIG. 20 shows an “H” strut end piece for hollow fin node (singlehollow).

FIG. 21 shows an “H” strut end piece for hollow fin node (doublehollow).

FIG. 22 shows a hollow fin node (single & double hollow) with strut andSEP attached to double hollow.

FIG. 23 shows a hollow fin node with notched strut attached to doublehollow.

FIG. 24 shows a solid single fin node.

FIG. 25 shows a solid single fin node FEA—Deformation.

FIG. 26 shows a solid single fin node FEA—Equivalent Stress.

FIG. 27A shows a single fin node and SEP (strut end piece).

FIG. 27B shows a single fin node with multiple SEP and struts.

FIG. 28 shows a solid single fin node with flats on main diameter.

FIG. 29 shows a solid single fin node with flats on main diameterFEA—Deformation.

FIG. 30 shows a solid single fin node with flats on main diameterFEA—Equivalent Stress.

FIG. 31 shows a solid single fin SEP (strut end piece).

FIG. 32 shows a solid single fin SEP (strut end piece) FEA—Deformation.

FIG. 33 shows a solid single fin SEP (strut end piece) FEA—EquivalentStress.

FIG. 34 shows a hollow single fin node “narrow”.

FIG. 35 shows a hollow single fin node “narrow”—FEA—Deformation.

FIG. 36 shows a hollow single fin node “narrow”—FEA—Equivalent Stress.

FIG. 37 shows a hollow single fin node “medium”.

FIG. 38 shows a hollow single fin node “medium” FEA—Deformation.

FIG. 39 shows a hollow single fin node “medium” FEA—Equivalent Stress.

FIG. 40 shows a hollow single fin node “wide”.

FIG. 41 shows a hollow single fin node “wide” FEA—Deformation.

FIG. 42 shows a hollow single fin node “wide” FEA—Equivalent Stress.

FIG. 43 shows a hollow single fin SEP (strut end piece) “wide”.

FIG. 44 shows a hollow single fin SEP “wide” FEA—Deformation.

FIG. 45 shows a hollow single fin SEP “wide” FEA—Equivalent Stress.

FIG. 46 shows a hollow single fin SEP “wide”—Thicker walls.

FIG. 47 shows a hollow single fin SEP “wide”—Thickerwalls—FEA—Deformation.

FIG. 48 shows a hollow single fin SEP “wide”—Thickerwalls—FEA—Equivalent Stress.

FIG. 49 shows a torque plate for solid node attached to series 5frame—Outside ISO view.

FIG. 50 shows a torque plate for solid node attached to series 5frame—Inside ISO view.

FIG. 51 shows a torque plate for solid node—Side view.

FIG. 52 shows a torque plate for solid node—Side ISO view.

FIG. 53A shows a torque plate for solid node, before attaching node—Topview.

FIG. 53B shows a torque plate for solid node, after attaching node—Topview.

FIG. 54 shows a torque plate for solid node—Back side.

FIG. 55 shows a torque plate for solid node, staged—Top OS detailedview.

FIG. 56 shows a torque plate for solid node, connected—Top OS detailedview.

FIG. 57 shows a torque plate for solid node, staged—Bottom centerdetailed view.

FIG. 58 shows a torque plate for solid node, connected—Bottom centerdetailed view.

FIG. 59A shows a torque plate for solid node print—Front view.

FIG. 59B shows a torque plate for solid node print—Side view.

FIG. 60A shows a hollow tube torque plate for solid node print—Frontview.

FIG. 60B shows a hollow tube torque plate for solid node print—Overheadview.

FIG. 61 shows a hollow tube torque plate for solid node print—Side view.

FIG. 62A shows rolling rib location concepts—STD system.

FIG. 62B shows rolling rib location concepts—Center RR with torque tube& additional foundations.

FIG. 63A shows rolling rib location concepts—Center RR with torque tube& no additional foundations.

FIG. 63B shows rolling rib location concepts—End RR with drives wheretwo frames attach and no additional foundations.

FIG. 64A shows rolling rib location concepts—End (both ends) RR withtorque tube & no additional foundations.

FIG. 64B shows rolling rib location concepts—End (one end) RR withdrives at every other two frame connection—half as many drives as infigure, no additional foundations.

FIG. 64C shows rolling rib location concepts—End (one end) RR withtorque tube.

FIG. 65 shows a Series 3 frame ISO view.

FIG. 66A shows a beam end connector—Side view.

FIG. 66B shows a beam end connector—Rotated side & end view.

FIG. 67A shows an angled beam outside connection—End view.

FIG. 67B shows an angled beam outside connection—Side view.

FIG. 67C shows an angled beam outside connection, with Strut—Top view.

FIG. 67D shows an angled beam outside connection bracket—Top view.

FIG. 68A shows collector tube upright connections—End view.

FIG. 68B shows collector tube upright connections—Side view.

FIG. 68C shows collector tube upright connections—Top end view.

FIG. 69A shows a mirror rail to mirror bracket—End view.

FIG. 69B shows a mirror rail to mirror bracket—End View.

FIG. 69C shows a mirror rail to mirror bracket—Side view.

FIG. 69D shows a mirror rail to mirror bracket—Top view.

FIG. 70A shows a mirror rail to beam connection—Side view.

FIG. 70B shows a mirror rail to beam connection—End view.

FIG. 70C shows a mirror rail to beam connection—Top view.

FIG. 70D shows a mirror rail to beam connection—Two piece mirror railconnection.

FIG. 71A shows pin & clip design concepts—End thread pin (multiplerevolutions) & Close clip.

FIG. 71B shows pin & clip design concepts—Full fine thread pin (multiplerevolutions) & Open clip.

FIG. 72A shows pin design concept—Full coarse thread pin (multiplerevolutions).

FIG. 72B shows pin design concept—Full coarse thread pin (singlerevolution).

FIG. 73A shows pin (single revolution) & clip design concept—Shown withclip in place.

FIG. 73B shows pin (multiple revolutions) & clip design concepts—Shownwith clip in place.

FIG. 73C shows pin (end thread—multiple revolution) & clip designconcepts—Shown with clip in place.

FIG. 74 shows SLIC Pin TM—Self locking pin.

FIG. 75 shows a solid node with solid fin print—Front view.

FIG. 76 shows a solid node with solid fin with loads—ISO view.

FIG. 77 shows a solid node with solid fin—ISO view.

FIG. 78 shows a solid node with solid fin—FEA (deformation).

FIG. 79 shows a solid node with solid fin—FEA (equivalent stress).

FIG. 80 shows a solid node with hollow fin print—Front view.

FIG. 81 shows a solid node with hollow fin—ISO view.

FIG. 82 shows a solid node with hollow fin—FEA (deformation).

FIG. 83 shows a solid node with hollow fin—FEA (equivalent stress).

FIG. 84 shows a single fin node assembly from patent application #1.

FIG. 85 shows a “knuckle” hollow fin node from patent application #3.

FIG. 86 shows a portion of a torque plate with a tube.

FIG. 87 shows a portion of a torque plate with a knob.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings wherein like reference numerals refer tosimilar or identical parts throughout the several views, and morespecifically to FIGS. 1, 7, 10 and 22 thereof, there is shown a node 10for a solar frame 44. The node 10 comprises an elongate portion 202 towhich a structural element 28 is attached. The node 10 comprises a fin12 extending radially outward from the elongate portion 202 where atleast 5% of the volume of the fin 12 is replaced by at least a singlevoid 204. The void 204 may extend essentially in parallel with theelongate portion. The elongate portion and the fin having a circlediameter less than 12 inches. The fin supports at least 200 lbs. ofload. It should be noted that depending on the circle diameter and thethickness of the fin, the fin is able to support loads of for enstanceat least 400, 800, 1600, 2500, 4000, 6000, 8000, 10000, or 12000 lbs.

The fin 12 may have a first leg 178 that extends outward from theelongate portion 202, and a second leg 180 that extends outward from theelongate portion 202 and adjacent to the first leg 178 with the void 204disposed between the first and second legs 178, 180. The fin 12 may havea third leg 182 that is connected to the first and second legs 178, 180and the first leg 178 is in spaced relation with the second leg 180. Thefirst, second and third legs 178, 180, 182 may form essentially arectangular cross-section. The first leg 178 may have a hole 184 and thesecond leg 180 may have a hole 186 which aligns with the hole 184 of thefirst leg 178 and through which the fastener 72 extends to fasten thestrut end piece 30 to the fin 12. The fin 12 may have a notch at itsends to provide clearance for and to receive the strut end piece 30. Theelongate portion 202 may be solid. The elongate portion 202 may be cubedshaped. The elongate portion 202 may have a channel 206 in which thestructural member is disposed and the void 204 is in the extrusiondirection.

The hollow profile shown does not represent any special technicaldifficulties. On an appropriately sized press (a 10″ 3300 US Tonextrusion press, for example), it can be tooled as a housing, porthole,taperseal or other type of hollow die with or without replaceableinserts. An extruder skilled in the art would be able have appropriatetooling and extrusion process parameters designed to successfullyextrude this profile.

Alternatively, the hollow fin design could be adapted to powdermetallurgical forming, machining, die casting, investment casting,forging, connection of multiple pieces by welding or other means adaptedto other means to produce a sleeve system with similar characteristics.In any of these, the use of the hollow fins will reduce the unsupportedspans, leading to reduced deflections and lighter weight parts,improving performance and reducing costs of the part.

The present invention pertains to a method for connecting a structuralelement with a strut 32 having a strut end piece 30 of a solar mirrorsupport frame 44. The method comprises the steps of attaching thestructural element to an elongate portion 202 of a node 10. There is thestep of attaching the strut end piece 30 to a fin 12 of the node 10extending radially outward from the elongate portion 202 where at least5% of the volume of the fin 12 is replaced by at least a single void 204extending essentially in parallel with a long axis or in the extrusiondirection. The elongate portion and the fin having a circle diameterless than 12 inches.

The fin 12 may have a first leg 178 that extends outward from theelongate portion 202, and a second leg 180 that extends outward from theelongate portion 202 and adjacent to the first leg 178 with the void 204disposed between the first and second legs 178, 180, and wherein theattaching step may include the step of inserting a fastener 72 through ahole 188 of a first strut end piece fin 192 of the strut end piece 30(see FIG. 8 ), a hole 184 of the first leg 178, a hole 186 of the secondleg 180 and a hole 190 of a first strut end piece fin 194 of the strutend piece 30 to fasten the strut end piece 30 to the fin 12, the hole188 of the first strut end piece fin 192 and the first leg 178 and thesecond leg 180 and the first strut end piece fin 194 in alignment.

The attaching step may include the step of placing the structuralelement in a channel of the elongate portion 202. The attaching step mayinclude the step of attaching the structural element to the elongateportion 202 which is solid.

The present invention pertains to a node 68 for a solar frame, as shownin FIGS. 75-85 . The node 86 comprises a solid elongate portion 132having fastener holes 24 to which a structural element is attached withfasteners to the elongate portion 132. The node 68 comprises a fin 12extending outward from the elongate portion 132 where at least 5% of thevolume of the fin is replaced by at least a single void 204 extendingessentially in parallel with the elongate portion 132.

There may be at least four fins 12, each of which has a void 204 of atleast 5%, disposed about the elongate portion 132, and the elongateportion 132 and the fins 12 have a circle diameter of less than 12inches. The circle diameter may be less than 8 inches. There may be atleast three fins 12, each of which has a void 204 of at least 5% and aleg disposed on each side of the void 132, and at least one of the fins12 has both of its legs attached to a leg of another fin 12. There maybe at least two fins 12, each of which has a void 132 of at least 5% anda leg disposed on each side of the void 132, and at least one of thefins 12 has at least one leg attached to a leg of another fin 12.

The torque plate can be manufactured from single or multiple pieces ofsteel or other appropriate material. Each of these single or multiplepieces could be a flat plate or a non-flat plate (tubular shape,C-channel, L-shape or other, for example); FIGS. 59A and 59B show asingle piece torque plate cut from plate steel while FIGS. 60A and 60Bshow a multiple piece torque plate manufactured from tubular steel (inthe embodiment shown, the “arms” of the cross are a tube which insertsthrough and is fastened to the “body” of the cross). The torque platehas a “knob” on one side which fits onto the top of a support (pylon forexample). The other side of the torque plate has one or more tubesattached to it into or onto which structural elements (nodes, forexample) of the solar frame attach. Depending on the size, geometry andloading requirements of the design, the knob, the tubes or both theknobs and tubes may be attached to one side of the torque plate (welded,for example, although other means are possible) (the knob on one sideand the tubes likely on the other, unless the structural parts of thesolar frame (nodes for example) pass through the torque plate and engagewith the tubes on the same side of the torque plate as the knobs). Ifthe geometry/loading, etc. require, the torque plate can have an opening(or openings) cut or bored into it, into which the knob, tube or tubesis placed, either with clearance or interference fit. The knob, tube ortubes can then, as appropriate, be attached to either the side of thetorque plate that the solar frame is on, the opposite side or bothsides, as structural analysis dictates. The present invention pertainsto an apparatus 208 for transmitting torque in a solar frame 44 havingstructural elements and a support, as shown in FIGS. 49-51 . Theapparatus 208 comprises a torque plate 114 having a first side and asecond side. The apparatus comprises a knob 116 attached to the firstside of the plate 114 for engaging the support. The apparatus comprisesa plurality of tubes 134 attached to the second side of the plate 114for receiving structural elements of the frame 44.

The present invention pertains to an apparatus 208 for transmittingtorque in a solar frame 44 having structural elements and a support, asshown in FIGS. 49-61 and 62A-64C and 86 and 87 . The apparatus comprisesa torque plate 114 having a first side and a second side. The apparatuscomprises a knob 116 which goes through and attaches to both the firstand second side of the torque plate 114 for engaging the support. Theapparatus 208 comprises a first tube 134 which goes through and attachesto both the first and second side of the torque plate 114 for receivingstructural elements of the frame 44. The apparatus comprises a secondtube which goes through and attaches to both the first and second sideof the torque plate 114. The apparatus 208 comprises a plurality ofadditional tubes which go through and attach to both the first andsecond side of the torque plate.

The present invention pertains to a system 210 for solar mirrors, asshown in FIGS. 62A, 62B, 63A, 63B, 64A, 64B and 64C. The system 210comprises a support, such as a pylon 198. The system 210 comprises afirst frame engaged with the support on which solar mirrors aredisposed. The system 210 comprises a second frame engaged with thesupport on which solar mirrors are disposed. The system 210 comprisesrotational means disposed on either side of each frame for rotating therespective frame. The system 210 comprises a first force applying means,such as a drive unit 136, for applying a force to the first frame tomove the first frame. The system 210 comprises a second force applyingmeans for applying a force to the second frame to move the second frame.

The present invention pertains to a node 10 for a solar frame 44, asshown in FIGS. 1, 7, 10 and 22 . The node 10 comprises an elongateportion 202 having a channel 206 extending through it in which astructural element is, disposed or a solid elongate portion onto which astructural element is disposed. The node 10 comprises a fin 12 extendingradially outward from the elongate portion 202 where at least 5% of thevolume of the fin 12 is replaced by at least a single void extendingessentially in the extrusion direction.

The present invention pertains to a node 68 for a solar frame, as shownin FIGS. 75-85 . The node 86 comprises a solid elongate portion 132having fastener holes 24 to which a structural element is attached withfasteners to the elongate portion 132. The node 68 comprises a fin 12extending outward from the elongate portion 132 where at least 5% of thevolume of the fin is replaced by at least a single void 204 extendingessentially in parallel with the elongate portion 132.

There may be at least four fins 12, each of which has a void 204 of atleast 5%, disposed about the elongate portion 132, and the elongateportion 132 and the fins 12 have a circle diameter of less than 12inches. The circle diameter may be less than 8 inches. There may be atleast three fins 12, each of which has a void 204 of at least 5% and aleg disposed on each side of the void 132, and at least one of the fins12 has both of its legs attached to a leg of another fin 12. There maybe at least two fins 12, each of which has a void 132 of at least 5% anda leg disposed on each side of the void 132, and at least one of thefins 12 has at least one leg attached to a leg of another fin 12.

The node can be manufactured from various materials and from variousmeans (extrusion, casting, die casting, etc.), but a likely means ofproducing the node would be through aluminum extrusion; the remainder ofthis paragraph will describe a typical manufacturing sequence for theextrusion process—depending on the specific facility and equipment,there could be changes to the process. Depending on the circle size andthe weight per ft. of the extrusion, and the availability of extrusionpresses available (tonnage, billet diameter, etc.), an appropriate pressand billet diameter will be chosen. For the hollow node/hollow fin andthe solid node/hollow fin (hybrid) nodes shown in various figures in thepatent application, for example, a press of 10 or 12″ diameter would beappropriate for the hollow node/hollow fin sized for the large designcriteria of that part, while a press of between 7 and 10″ could beutilized for the hybrid node. The selection of billet diameter and pressmust be capable of producing the part; various selections may bepossible, and chosing among them often is a matter of cost and equipmentavailability. A hollow extrusion die (porthole, taperseal or housingdie) is designed and purchased. Depending on the alloy and facilitycapabilities, an appropriately sized billet is heated and delivered tothe press and placed into the container. Each extrusion facility hasoperating practices which dictate temperatures, speeds, quench rates,stretching rates, aging practices, etc. The extrusion press compressesthe billet against the die and when appropriate tonnage is reached, theextrusion of the metal through the die proceeds. Often the part iscooled from an elevated temperature and then stretched (straightened).The profile is then cut to appropriate length at the finish saw andstacked into an aging rack for subsequent artificial aging (heattreating). After aging the part is likely cut to a shorter length andthen fabricated to produce the fastener holes, any notches or finremoval required.

In the operation of the invention, the present invention builds uponpatent application Ser. Nos. 12/583,787; 12/587,043; 12/798,757 and12/927,813, all of which are incorporated by reference herein. In theseprior applications, there was included:

-   -   Mirror Support Structures using tubes 28 loaded axially    -   Modified I-beams as mounting means for Mirror Support Structures    -   Configuration of Main Supports/Longitudinal Members and        Connectors    -   Strut 32 Designs    -   Strut end piece 30 concept and design    -   Means of fastening Strut end piece 30 to Connectors—via—pins 56,        rivets, bolts or other fasteners, flat-to-flat    -   Fabrication and Assembly methodology    -   Automatic mirror cleaning/water collection/reclamation system    -   Single Fin Sleeve    -   Guided Insertion Strut end piece    -   Swaged Strut End Connection    -   Angled “Knuckle” Hinge Connector and    -   Additional Alternative Strut and Strut end piece Designs

The present invention covers the following aspects of the concentratedsolar power frame 44 design:

-   -   Hollow single fin node 10    -   Hollow single fin node 10 design utilizing chord 28 and chord        end piece 26—vs—through chord 28 (including more detail on node        designed to best accommodate the hollow single fins 12)    -   Torque plate 114 solid node 106 design    -   Rolling rib 142 location concepts    -   Other design elements:        -   Beam 36 and Beam end piece 34 Connector design        -   Angled Beam 36 w/Beam end piece 34 on one end/bracket 158 on            the top, eliminating extra piece beyond Nodes A & B        -   Mirror Support Rail and Bracketry designs        -   Mirror rail to mirror bracket 162 designs        -   Mirror rail to Beam connection 164, 166 designs        -   Collector tube upright 152 connection designs        -   Pin 56 and clip designs

The current invention builds on prior designs of single fin sleeves andguided insertion strut end including modifications to the design of thesingle fin/strut end connection through the use of hollow fins 12. Thestrut 32 assemblies must carry tensile and compressive loads which varywidely as the frame 44 rotates to follow the path of the sun and asenvironmental conditions (e.g. wind) change; the space frame 44 and itscomponents are designed to carry the maximum working and storageposition loads (the frame 44 can be “stowed” to withstand high winds,but isn't collecting solar energy during this time). The prior singlefin and strut assembly (including the guided insertion design) carrythese loads and transfer them through the strut 32, to the strut endpiece 30 (if used) and then into the node 68 (hereafter called “sleeve68”) via the sleeve fins 90.

The present invention also contains details of how the segmented chords28, solid nodes 106, torque plates 114, collector tube uprights 152 andvarious other solar frame 44 components are designed.

Hollow Single Fin Node 10

The hollow single fin 12 design shown in FIG. 1 enables these loads tobe “split” between each leg of the hollow fin 12, transferring the forcefrom the strut 32 to each leg. Designs with the hollow sleeve single finhave more evenly distributed loads around the periphery of the nodesleeve 68 and thus has shorter unsupported spans 14 of the sleeve 68material between the fins 12, resulting in lower deflections andstresses. For solid elongate nodes, the hollow sleeve single fin providea more linear transfer of the axial forces from the structural elementsattached to them as well as increased resistance to side-loading wherethe fin is used in this manner (for a beam or beam end piece connection,for example). Circle sizes 94 of the hollow single fin 12 sleeves 68 arealso reduced due to the geometry of where the legs meet the sleeve body,which aids extrudability and the size of the press that the profile canbe run on (the fin 12 length is determined by the fasteners 72 andrequisite hole-to-edge distances for both the fin 12 and for the matingstrut end piece fins; because hollow fins 12 “radiate” out from the nodesleeve 68 on either side of what would be a central single solid fin 90,they attach to the sleeve 68 as the profile “pulls back” from thetangent point of the single solid fin 90, leading to a smaller extrudedcircle size 94). If the design calls for a strut end piece 30, designdetails will show that for the same weight of part, the deflections andstresses are lower. The only downsize to the design is a slight increasein extrusion difficulty, which could manifest itself in slightly slowerextrusion velocities.

The frame 44 design utilizing segmented chords 28 has been described inprior patent applications. This invention provides additional designconcepts re: the chord end piece 26 to node design, showing a goodembodiment of a hollow (or solid) node elongate portion utilizing hollowsingle fins 12 onto which the struts 32 attach, often utilizing strutend pieces 30, as shown in FIG. 9 .

FIG. 10 shows Node C 122 as fabricated (cut to length, notched for strutend piece 30 interface and fastener holes 24 shown), with the chord endpieces 26, beam end pieces 34 and strut end pieces 30 shown with theirassociated chords 28, beams 36 and struts 32 also shown.

The rolling rib 142 concept was disclosed in prior patent applicationwork. The present invention builds on this, showing possible additionalmounting locations for the rolling rib 142, as shown in FIGS. 13, 14 and63B. The use of a torque tube 140 providing motive force to the frame 44via a rolling rib 142 eliminates the “frame-on-frame” induced torque,which adds greatly to the RMS slope error (optical mis-alignment) of theframe 44. Frame 44 analyses has shown that much of the slope error RMSis due to deformation from the effect of additional frames applyingtorque to the frame(s) between them and the drive; the rolling rib 142eliminates this.

Mounting the rolling rib 142 in the center of the frame 44 may requireadditional foundations 138 to support the torque tube 140 and potentialroller housings 38 as shown in U.S. patent application Ser. No.12/583,787. By incorporating the rolling rib 142 into one or both endsof the frame 44, the torque tube 140 supports and roller housings 38 canbe incorporated in the pylon 198 design.

Other Design Elements:

-   -   Beam 36 and Beam end piece 34 Connector design    -   Angled Beam 36 w/Beam end piece 34 on one end and bracket on the        top, eliminating the extra piece beyond Nodes A and B    -   Mirror Support Rail and Bracketry designs    -   Mirror rail to mirror bracket 162 designs    -   Mirror rail to Beam connection designs    -   Collector tube upright 152 connection designs

As the design work for the solar frames 44 progressed, additional designfeatures of some of the parts were developed; these use easy to extrudeprofiles designed for ease of fabrication and assembly; designed to meetthe exact loading needs of the parts. Some of these concepts weredisclosed in earlier patent application work—this invention providesadditional detail.

Hollow Single Fin Node 10

FIGS. 18A, 18B and 18C show both direct strut 32 to sleeve fin 12connections, reinforced strut 32 with plates 88 at sleeve fin 12connections and separate strut 32 to strut end piece 30 to sleeve fin 12connections.

FIG. 19 shows a strut 32 attached to hollow single fin 12 of sleeve 68also having a hollow double fin 196.

FIGS. 20 and 21 show early renditions of strut end pieces 30.

FIG. 22 shows a strut 32 attached with a pin 56 to hollow double fins196 of sleeve 68 with strut end piece 30 showing how a narrower strut 32can attach to a wider connection point if needed.

FIG. 23 shows a strut 32 attached to hollow double fins 196 of sleeve68.

The present invention further advances the design of the single fins ofthe sleeve 68 and the mating strut end piece fins.

The present invention focuses on improvements to the design of thesleeve 68 single fins 12 and mating strut end pieces 30. The designshown in FIG. 24 and the figures which follow uses four solid fins 90,tapered where they meet the elongate portion 202 and at the tips 80,thicker in the middle; depending on the frame 44 geometry and sleeve 68location, fewer or greater numbers of fins 90 may be utilized. Themaximum thickness 84 (center bulge) of each fin 90 is designed toaccommodate the tensile and compressive forces carried through thefastener 72—the interface between the pin 56 and the sleeve 68 fin 90location determines the point of bearing stress and defines the crosssection required at this point; generally, the thickness is defined bythis maximum permissible bearing stresses at the fastener 72 interface,although stress at net section or block shear calculations could be thelimiting factor. The fin(s) are thinner at the fin base 78 where theymeet the elongate portion 202 to save material (cost and thisshape/circle size 94 will tax the capabilities of an extrusion operationcapable of utilizing 10″ diameter billets—there are many such pressesbut fewer of a larger size, which would limit production onto fewer (andcorrespondingly more expensive facilities). The same philosophy (reducetotal weight) would exist whether attempting to produce parts onextrusion presses larger or smaller than 10″ diameter The fin(s) taperat the tips 80 both to limit weight of the sleeve 68 and to make theassembly of the strut 32 assemblies onto the fin easier (the strut 32assemblies (Strut 32+2 end pieces) can be large, heavy and bulky andsome may require two hands to manipulate—the tapered fin end and “guidedinsertion strut end piece” (inventions in the prior patent application)help to accomplish this. The minimum “tip” thickness is defined by theblock shear calculation done if the strut end piece 30 is in tension(how much fin 90 material is needed to ensure that the “fastener”doesn't tear out a “block” of it). A, B, C and D are unsupported spans22 between the solid fins 90 in FIG. 24 . The forces relative to thefins 90 converge at common point 76.

The iterations done as part of the invention confirmation which followsuse the minimum required bearing stress calculated thickness spreadacross a single fin and through a hollow single fin 12 with total wallthicknesses equal to this minimum.

The hollow-fin(s) 12 of the sleeve 68 allow the tensile and compressiveforces of the strut 32, transferred directly to the sleeve 68 or throughstrut end pieces 30 to be more “linear” with less focusing down of the“width” of the forces from the full cross section of the strut 32 to thesleeve fin. The forces also act on the sleeve 68 in a different fashion,with the hollow creating ½ of the force acting in two locations. Notethat the hollow fin 12 can have parallel sides (a simple box type) orcan have non-parallel sides (in fact each wall can be of constant orvarying cross section as best meets the design criteria for theparticular part), mimicking the sleeve fins shown previously; these actin concert with the guided insertion strut end pieces 30 or even withsimple slotted struts 32 in a manner to make assembly of the frame 44simpler, as the curve presents a “guide” to help slip the sometimeslarge, bulky, heavy struts 32 and strut 32 assemblies onto the sleevefin(s) for fastening.

TABLE 1 POSITIONS OF UNSUPPORTED MAX. MAX. DESCRIPTION MAX. SPAN BETWEENLBS MAX EQUIV EQUIV (WALL FIN FINS CIRCLE PER DEF STRESS STRESSTHICKNESS) WIDTH A B C D SIZE FT (IN) (KSI) (KSI) SSF .300 0.89 3.5 2.41.8 2.4 8.9 9.1 0.012 44,336 21,150 SSF .225 0.89 3.6 2.5 1.8 2.5 9.19.6 0.010 42,102 21,000 TO .375 HF- 1.66 2.9 1.6 0.9 1.6 8.8 9.9 0.00734,301 14,000 NARROW .300 HF-MED. 1.91 2.7 1.4 0.6 1.4 8.8 9.9 0.00629,402 14,500 .300 HF WIDE 2.05 2.6 1.2 0.5 1.2 8.7 9.7 0.006 30,23819,850 .300 HF WIDE 2.16 2.4 1   0.2 1   9.5 10    0.005 27,166 10,700.865 PIN .300 SSF-SEP 1.09 NA NA NA NA 8.4 8.7 0.005 21,746 14,750 H FWIDE- 2.15 NA NA NA NA 8.5 8.3 0.005 28,436 18,400 SEP H F WIDE 2.15 NANA NA NA 8.5 8.7 0.004 18,209 14,000 SEP SSF = SINGLE SOLID SEP = STRUTEND HF = HOLLOW FIN (NUMBERS HAVE BEEN ROUNDED UP)

Table 1 shows the various profile designs and resulting lbs/ft weight,circle size 94, deformation and stress levels (assuming a 12,000 lb.maximum tensile or compressive force, used for the examplecalculations). Note that the “single solid fin 0.225 to 0.375” wallresults in believed acceptable levels of deformation (0.0097″) underfull load and stress (21,000 psi—which is just below the maximumpermissible taking acceptable safety factors into account). As the fin90 is hollowed and the hollow portion becomes wider, the forces arespread more evenly along the interior “periphery” of the sleeve profile,and the unsupported spans 22 are reduced, leading to improved maximumdeformation and stresses (the “best case”, for this particular designwould appear to be the “medium width” hollow fin 98).

The strut end pieces 30 associated with the single solid fin 90 and thewide width hollow fin 100 are similar, although slightly better for the“wide hollow fin 100”, holding the weight per ft. of the part constant.

FIGS. 25 and 26 show the design, deformation and stresses for a singlefin sleeve designed to encompass a tubular chord 28 or for use withchord couplers or chord end pieces (profile designs other than a simplecircular shape would show similar effects). The 0.300″ wall thickness ofthe portion which would surround the central chord 28 was held constantin all designs to better understand how varying the hollow fin widthaffects the results (except for the next one, which was specificallymodified in attempts to reduce the total weight of the sleeve profile tokeep it readily extrudable on a 10″ diameter extrusion press (12,000 lb.max tensile or compressive force)).

FIGS. 28, 29 and 30 show the design, deformation and stresses for asingle fin sleeve designed to encompass a tubular chord 28 or for usewith chord couplers or chord end pieces. The wall thickness of theportion which would surround the central chord 28 was specificallymodified in attempts to reduce the total weight of the sleeve 68 profileto keep it readily extrudable on a 10″ diameter extrusion press (12,000lb. max tensile or compressive force loading on the highest loadedstructural element attached to the sleeve).

FIGS. 31, 32 and 33 show the cross sectional design, deformation andstresses of a strut end piece 30 designed to work with the single finsleeve design (12,000 lb. max tensile or compressive force).

FIGS. 34, 35, 36, 37, 38, 39, 40, 41 and 42 show the design, deformationand stresses for a single fin sleeve designed to encompass a tubularchord 28 or for use with chord couplers or chord end pieces, with thefins being hollow; the first three are for a “narrow” hollow fin 96, thenext three for a “medium” hollow fin 98 and the remaining three for a“wide” hollow fin 100 design. Note that as the hollow portion widens,the unsupported portion 14 of the profile surrounding the central chord28 narrows. The 0.300″ wall thickness of the portion which wouldsurround the central chord 28 or mate with the chord couplers or chordend pieces was held constant in all designs (except for the next one,which was specifically modified in attempts to reduce the total weightof the sleeve profile to keep it readily extrudable on a 10″ diameterextrusion press (12,000 lb. max tensile or compressive force); the0.300″ wall was held constant to better understand the effects ofvarying the hollow fin width. A, B, C and D in FIGS. 34, 37 and 40 areunsupported spans 14 between the hollow fins. The nodes shown in thesefigures are hollow nodes, which geometrically create more space for thelegs of the hollow fins to attach; solid nodes can be used, depending onthe geometric design.

FIGS. 40, 41 and 42 show the design, deformation and stresses for asingle fin sleeve designed to encompass a tubular chord 28 or for usewith chord couplers or chord end pieces, with the fins 90 being hollow;this particular design mimics the “wide” hollow design, but shows theresult of using a larger fastener 72 diameter. The 0.300″ wall thicknessof the portion which would surround the central chord 28 was heldconstant in all designs to better understand the effects from varyingthe hollow single fin width (12,000 lb. max tensile or compressiveforce).

FIGS. 43, 44 and 45 show the cross sectional design, deformation andstresses of a strut end piece 30 designed to work with the single finsleeve design with a wide hollow (12,000 lb. max tensile or compressiveforce). The profile was designed to acceptable levels of deformation andstress, resulting in a part lighter than the single fin (solid) strutend piece 30 than it replaces. Designs for narrow or medium hollowsingle fins 12 would yield similar design concepts.

FIGS. 46, 47 and 48 show the cross sectional design, deformation andstresses of a strut end piece 30 designed to work with the single finsleeve design with a wide hollow (12,000 lb. max tensile or compressiveforce). The profile was designed to weigh the same as the single fin(solid) strut end piece 30 that it replaces, and thus results inslightly lower levels of deformation and stresses.

FIG. 11 is a partial view of one geometry of a space frame 44 design forCSP parabolic mirror systems showing 3 (of 7 for this design) slices104, utilizing 7 nodes (Node A 118, Node B 120, Node C 122, Node D 124,Node E 126, Node F 128 and Node G 130 are shown for each “slice” 104 inthis graphic, with 2, diagonal beam 110 and one horizontal beam 108 perslice 104, with two (of 6) chords 28 connecting each of the 7 “slices”with the adjacent. For clarity, there are 6 “segmented chords” betweenthe 7 slices at each of the 7 nodes=42 “segmented chords”—only two areshown in this graphic (the ones which could have been shown at nodes A,D, E and G were omitted to make the “slices” 104 more visible). Theslices are connected with segmented chords 28 connecting each node withthe node of the same letter of the next slice 104. A multitude of struts32 connecting the various nodes are also shown.

FIG. 12 is a partial view of one geometry of a space frame 44 design forCSP parabolic mirror systems showing 3 (of 7 for this design) slices104, utilizing 7 nodes (Node A 118, Node B 120, Node C 122, Node D 124,Node E 126, Node F 128 and Node G 130 are shown for each “slice” 104 inthis graphic, with 2 diagonal and one horizontal beams 108 per slice104, with two (of 6) chords 28 connecting each of the 7 “slices” withthe adjacent slice 104. For clarity, there are 6 “segmented chords”between the 7 slices at each of the 7 nodes=42 “segmented chords”—onlytwo are shown in this graphic (the ones which could have been shown atnodes A, D, E and G were omitted to, make the “slices” more visible). Amultitude of struts 32 connecting the various nodes are also shown.

FIG. 2 is an end view of the node 10 at position C, showing the Channel206 to accept the chord end piece 26 or chord and the four (in thiscase) hollow single fins 12 onto which the struts 32, via strut endpieces 30 in many cases, and beams 36, using bean-rend pieces 34, inmany, cases, fasten. Note how the unsupported span 14 between the hollowfins 12 is much less than if they were solid fins 90. This reduces thedeflections and stresses from deformation(less deflection in thecircular'ish (as shown) “body” of the profile). Material is removed at20 to reduce the weight of the node 10, and material is thickened at 112for bearing stress requirements of node 10 to chord end piece fastenerconnection.

FIG. 3 (end view) shows Node C 122 as fabricated (cut to length, notchedfor strut end piece 30 interface and fastener holes 24 shown), with thebeam end pieces 34 and strut end pieces 30 shown with their beams 36 andstruts 32 also shown.

FIG. 4 shows Node C 122 as fabricated (cut to length, notched for strutend piece 30 interface and fastener holes 24 shown). A chord end piece26 is shown inserted into the channel 206 of the node 10.

FIG. 5 (end view) shows Node C 122 as fabricated (cut to length, notchedfor strut end piece 30 interface and fastener holes 24 shown), with thechord end piece 26, beam end pieces 34 and strut end pieces 30 shownwith their associated chord 28, beams 36 and struts 32 also shown.

FIG. 6 shows Node C 122 as fabricated (cut to length, notched for strutend piece 30 interface and fastener holes 24 shown). A chord end piece26 is shown inserted into the channel 206 of the node 10 with a chord 28on the chord end piece 26.

FIG. 7 shows Node C 122 as fabricated (cut to length, notched for strutend piece 30 interface and fastener holes 24 shown). A chord end piece26 is shown inserted into the channel 206 of the node 10 with a chord 28on the chord end piece 26 and a chord end piece 26 with chord 28 shownon the hollow single fin 12. Note that the tensile and compressiveforces from the space frame 44 transfer through the strut 32 and chords28 to the strut end pieces 30 and chord end pieces 26 and then to thenode fins 12 or node center. These force transfers are designed tocreate a substantially single point where the forces converge. Thehollow fin concept allows the strut 32 forces to transfer to theindividual legs of the hollow fin 12, reducing the unsupported span 14between fins 12, reducing the deflections and stress on the part.

FIG. 8 shows Node C 122 as fabricated (cut to length, notched for strutend piece 30 interface and fastener holes 24), with the chord end pieces26, beam end pieces 34 and strut end pieces 30 shown (chords 28, beams36, and struts 32 are not shown).

FIG. 10 shows Node C 122 as fabricated (cut to length, notched for strutend piece 30 interface and fastener holes 24), with the chord end pieces26, beam end pieces 34 and strut end pieces 30 shown with theirassociated chords 28, beams 36 and struts 32 also shown. It also showshow all force vectors will converge at a common point within the node10.

FIG. 49 shows a system 208 comprising the solar frame 44 (nodes 10,chords 28, beams, 36 struts 32) attached to one concept of a torqueplate 114. The frame 44 is supported at each end and able to rotateabout the center of mass, approximated by the “knob” shown on theoutside of the torque plate 114. The torque plate 114 is designed toattach to specific nodes of the frame 44 (the outside of Nodes C 122,Node D 124 and Node G 130 on slices 1 and 7 in the example used).Generally the individual solar frames are grouped so that a centraldrive mechanism turns one frame on either side of the drive via theadjacent torque plates 114, which are hung by the “knobs” fromstructural pylons equipped with bearings. The torque plate 114 appliesthe rotational torque to the frame (resisting wind and gravity forces),which rotates the frame 44. At the other end of the frame 44, the torqueplate 114 is attached to the torque plate 114 of the adjacent frame 44via the “knobs”, and thus turns that frame 44 and any other frames suchattached along the line at the same time as the first frame. The torqueplates 114 must resist hundreds of thousands of in-lbs of torque toaccomplish this (additive as a 2^(nd), 3^(rd), 4^(th), 5^(th), 6^(th) ormore frames are attached in a line on either side of the common centraldrive (which thus drives 2, 4, 6, 8, 10, 12 or more frames)). FIGS. 50,51, 52, 53A, 53B, 54, 55 and 56 show the details of the nodes 10 andattachment means to the torque plate 114. The Torque plate 114 is afabricated part, likely steel plate or fabricated metallic structuralelements. The connection shown is one of many that could be used. Theconcept here is to use an extruded solid node with a circular extrusionto fit within tubular attachments of the torque plate 114, fastenedtogether, at Nodes C, D and G. Other orientations, Node selections(depending on frame geometry), etc. are certainly possible—thisrendition is for explanatory purposes.

FIGS. 51 and 52 show close-ups of the node 10 and torque plate 114attachment.

FIG. 53A shows nodes C, D and G before insertion into torque plate 114attachment tubes 134; FIG. 53B shows afterwards, before fastening.

FIGS. 57 and 58 show where Node G 130 inserts into the attachment tube134, which is part of the fabricated torque plate 114 (attachment tube134 could be welded on to torque plate 114, inserted into a bored holein the torque plate 114 then welded, etc.).

FIGS. 57 and 58 also show a good view of the fabricated solid nodeextrusion, showing how the extruded shape with the solid central portion132 at the left has the “fins” machined off of both ends, with the rightside of the node G 130 further machined into a flat or “guidedinsertion” plate (if this feature is desired (not shown)), onto whichthe chord end piece 26 will be fastened. Appropriate fastener holes 24are fabricated into the ends of the node 10, and into the fins.

FIGS. 59A and 59B show steel torque plate 114 design.

FIGS. 60A, 60B and 60C show torque plate 114 design fabricated/assembledfrom hollow steel tubes.

TABLE 2 SPEED 20MPH 50 MPH 80 MPH MOUNT PLATE TUBE PLATE TUBE PLATE TUBESTRUT WEIGHT (LBS)    325    318    570    546      868      832 BEAM,MR & MISC.    324    324    502    502      927      927 WGHT (LBS) MAX.TORQUE 150,591 150,067 967,773 970,171 2,519,197 2,520,842 APPLIED(IN-LBS) MAX. SHEAR AT  2,074  1,722  7,825  9,974    20,674    24,399PIPE/NODE (LBS) MOUNT DIMENSIONS (IN) A (OR SECTION 1) 12 HSS HSS HSS 9× 3 × 5/16 20 14 × 6 × 5/16 28 18 × 6 × 5/16 B 5 N/A 11 N/A 17 N/A C 10N/A 16 N/A 22 N/A D (OR SECTION 2) 6 HSS 10 HSS 14 HSS 5 × 3 × 5/16 8 ×3 × 5/16 12 × 4 × 5/16 E 8 N/A 12 N/A 16 N/A F 17.217 16.705 12.232 129.014 9.524 G 1.66 1.66 2.88 2.88 3.5 3.5 H 1.28 1.28 1.77 1.77 2.3 2.3I 1.5 1.5 1.75 1.75 2.25 2.25 MOUNT WGHT (LBS) 452 444 730 682 998 845STEEL PIPE WGHT 2 7 12 39 21 64 (LBS) ALUM.NODE WGHT 8 8 9 9 16 16 (LBS)MAX. SLOPE ERROR 2.959 2.968 4.112 3.718 5.792 5.077 AVERAGE SLOPE 2.32.307 2.918 2.674 3.728 3.295 ERROR

In regard to Table 2, as wind loads vary along the width of the frame 44they create a torque that must be resisted at the frame's end. Forframes that are rotated with conventional technologies this torqueaccumulates as the frame 44 gets closer to the drive system. Forexample, if wind loads on a single frame create 200,000 lb-in of torque,the frame 44 nearest the driving mechanism where there are five framesper side would be loaded with 1,000,000 lb-in of torque. Frames thathave fewer frames per drive or use a rolling rib 42 system, etc. canhave an applied torque as small as 125,000 lb-in. Larger frames locatedin hurricane prone regions can see torques up to 6,250,000 lb-in. Toresist this torque steel plates or tubes are mounted on the end of eachframe 44 and are supported by a pylon 198 at a single point. Thesemounts also play a significant role in limiting the deflections whichcontribute to the frame's optical efficiency. The plates can be cut outfrom a single piece of steel or created by welding together smallerpieces. The tubes are selected from standard steel shapes, typicallyHSS. Attaching the torque plate 114 to the frame 44 is done by insertingand bolting the aluminum node into a steel pipe which has been welded tothe torque mount. Large shear forces are present at this connectionpoint which cause bending moments that the steel pipe and aluminum nodeneed to be designed to resist. The tables above summarizes the appliedforces and designs for a 12 meter frame 44 which is closest to the drivemechanism 136 and is connected to four additional frames subjected towind loads of 20, 50, and 80 mph. These wind loads were applied to theframe 44 in all orientations, with larger wind loads applied in the stowposition. The results show the significant difference that a 30 mphchange in wind speed has on the applied torque of the frame 44.Consequently, the shear force at the node connection and the size of thenode and steel pipe increase as the wind speed increases. Using a tubefor the mount has significant advantages over a plate for the frameloads at 50 and 80 mph. The tubes are lighter than the plates for frameswith the same wind speeds and the optical efficiency is greater. Theweight of the steel pipes used to attach the node 10 to the mount isgreater because the pipe must pass through the tube for connectionpurposes, but this small amount of added weight is offset by the largereduction in the mount weight. These benefits diminish with the decreasein wind speed. For the frame 44 subject to 20 mph wind speeds, there isa negligible difference in aluminum and mount weight and the opticalefficiency is slightly worse on the frame 44 using a tube mount asopposed to a plate mount. A tradeoff to reduced steel weight andimproved optical efficiency is that the overall frame length must bereduced to accomodae the tube—vs—plate thickness; holding the collectortube lengths constant, this causes the linear length of mirrors to bereduced.

FIGS. 62 a, 62 b, 63 a, 63 b, 64 a, 64 b and 64 c are designed toexplain six different philosophies to rotate the solar frames to followthe sun (only four frames are shown in each so that the graphics areviewable on the printed page):

1. Conventional Drive 136 with Torque plates 114 at each end of eachframe 44, where one drive unit 136 drives 1, 2, 3, 4, 5 or even 6 ormore frames on either side of the drive; the frames nearest the driveare subject to the most torque, as they must rotate themselves and theother frames attached to them, etc. See FIG. 62A.

-   -   These conventional units induce a LOT of torque in the frames        nearest the drive, decreasing to the torque required to rotate a        single frame for the frame that is furthest from the drive. If        the torque is listed as “T” (usually about 150,000 in-lbs), and        there are 5 frames on either side of the drive unit 136, then        the units nearest the drive unit 136 will have their own torque+        the “applied torque” of 4 T (600,000 in-lbs). This large amount        of torque causes the frames to deform and causes increased slope        error (focal accuracy measure: large values of slope error        result in reductions in optical efficiency).    -   The Torque Plates 114 at either end of each frame 44 are subject        to VERY large loads and are thus relatively heavy and        expensive—vs—what would be required were their only requirement        be to “hang” the frames and let them rotate.

2. Rolling rib 142 centrally located on each frame 44, with therotational motive force from a “Torque tube 140” which individuallyengages with each rolling rib 142. The centralized rolling rib 142 mayhave additional foundation 138 requirements, particularly if the rib 142is designed to minimize deflection from wind and weight in addition tojust applying the torque to each frame 44, centrally and singly. SeeFIG. 62B.

3. When a torque tube 140 is used to drive the rolling rib 142 in thecenter of the frame 44, each frame 44 receives the same torque, and itis applied in the center of the frame 44, minimizing the deformation andoptimizing the slope error. In addition, if there are foundations 138under the center of the frame 44, the rolling rib 142 can be utilized asdisclosed in WES's 2^(nd) patent application, U.S. patent applicationSer. No. 12/587,043, which will enable the rollers 46, as shown in FIGS.14A and 14B, to also reduce the deformation from the wind/weightdeflecting the center of the frame 44. See FIG. 63A.

4. Frame 44 with a rolling rib 142 at each end of each frame 44, withindividual drive units 136 at each pylon driving a rolling rib 142 oneach of the 2 adjacent frames. See FIG. 63B.

-   -   In FIG. 63B when there is a driven rolling rib 142 on each end        of each frame 44, there is no need for additional foundations        138 in the center of the frame 44—the pylon foundations 138 do        “double duty” and can be used to stabilize a drive unit 136        designed to drive the frame 44. Because the frame 44 is driven        from both ends, there is, in effect, only ½ the length of the        frame 44 subject to the rotational torque deformation effects,        leading to deformations from this similar to FIG. 62B above.

5. Frame 44 with a rolling rib 142 at each end of each frame 44, with aTorque tube 140 drive providing motive force to each rolling rib 142unit. See FIG. 64A.

-   -   FIG. 64A is very similar to FIG. 63B, but with fewer drive units        136, as the drives can utilize a Torque tube 140 to provide the        motive force to the rolling ribs 142; this leads to less        electrical and controls installation and fewer drive units 136        per field.

6. Frame 44 with a rolling rib 142 at only one end of each frame 44,with individual drive units 136 at every other pylon driving a rollingrib 142 on each of the 2 adjacent frames. See FIG. 64B.

-   -   In the case shown in FIG. 64B, the drive units 136 can share the        pylon 198 foundations 138, but each frame 44 is subject to the        full torque (T) across its full length, leading to larger        rotational deformations than in 2, 3, 4 or 5 (although there are        of course ½ the number for drives and rolling ribs 142 per field        as in FIG. 63B).

7. Frame 44 with a rolling rib 142 at only one end of each frame 44,with a Torque Tube providing motive force to the rolling ribs 142 atevery other pylon location, rolling rib 142 on each of the 2 adjacentframes. See FIG. 64C.

-   -   FIG. 64C is a very similar concept as FIG. 64B, but with drives        utilizing torque tubes to provide the motive force to the        rolling ribs 142, resulting in even fewer drive units 136.

Table 3 details analytical results from various frame 44 analyses,supporting some of the 7 cases noted above, showing the different drive,foundation 138 and rolling rib 142 options:

TABLE 3 FRAME SPECIFICS FRAME WEIGHT SLOPE ERROR FROM MODEL (RMS) WGHTOF EST. WGHT AT NOT AT CALCULATED FRAME # OF IDEALIZED OF TOTALPHERIPHERY PHERIPHERY FILED TYPE FRAMES STRUTS, FRAME (NO TORQUE OFFIELD OF FIELD AVERAGE (STD OR EACH CHORDS, TORQUE PLATE WORST AVG.WORST AVG. WORST AVG. MODEL ROLLING SIDE OF BEAMS PLATES) WEIGHT LOADLOAD LOAD LOAD LOAD LOAD ID RIB) DRIVE ETC. (LBS) (LBS) (LBS) CASE CASECASE CASE CASE CASE 7T7B STD 1 1071 1369 572 2.97  2.11  2.681 1.8432.75  1.91  2 3.21  2.35  2.769 1.994 2.88  2.084 3 3.51  2.66  2.9442.171 3.09  2.292 4 4.15  2.99  3.186 2.375 3.43  2.528 5 4.8  3.34 3.601 2.597 3.9   2.783 7T7B CENTER NA 945 1236 435 3.171 1.890 2.6711.696 2.796 1.744 RR CENTER 947 1238 435 3.087 1.907 2.690 1.710 2.7891.759 RR ONE 951 1260 435 3.135 2.230 2.686 1.694 2.798 1.828 SIDE RRTWO 996 1331 435 2.921 1.942 2.645 1.739 2.714 1.790 SIDE RR ALL FRAMESWERE WES SERIES 5 12 METER-MIRROR TYPE RP3 METHODS FOR CALCULATING SLOPEERROR HAVE CHANGED SINCE PROVISIONAL PATENT WAS FILED. RESULTS REMAINSIMILAR IN RELATION TO EACH OTHER, BUT ARE MUCH SMALLER IN MAGNITUDE(BETTER OVERALL PERFORMANCE)

Frame 44 geometries were established and analysis models were run. Theresults from these analytic calculations allow us to model an“idealized” frame 44 (e.g. the members are, for example, simple tubularstruts 32 and chords 28 and relatively simple box beams 36). Conversionof the “idealized” members to actuals may add some weight to the frame44.

The output from the frame 44 analytic work enables us to compare theexpected results of the frame 44 performance in terms of slope error(the difference between perfect alignment between the reflected solarrays onto the collector tube). The output from the frame 44 analyticwork also enables one to understand the exact design requirements foreach strut 32, chord 28 and beam 36, by looking at multiple load casesas defined by ASCE-7, with the frame 44 oriented in various positions,with the wind blowing both on the surface of the mirror and at the backof the mirror, for this analysis, 35 MPH wind speeds are used tocalculate optical efficiency (slope error) in any orientation; 50 MPHwind speeds in any orientation and 90 MHP wind speeds in the “stowage”position (rotated such that the system points the mirrors 45 degreesbelow the horizon line (135 degrees from pointing straight up) withpairs of mirror rows pointed at each other to “buffer”) the mirrors areused to determine the maximum compressive and tensile forces and bendingmoments that each chord 28, strut 32 and beam 36 will be subject to:this is used to design the members. While the specific frame 44geometry, wind speed, frame 44 orientation/rotation, etc. discussedabove are the basis of the table above the text, the concepts disclosedwill apply to other criteria if wind speed, frame 44 rotation, frame 44design, rotational motive force application, etc. are considered.

In WES's 2^(nd) patent application, Ser. No. 12/587,043, there isdisclosed the concept of the rolling rib 142, detailing the curved riband support rollers 46 constraining the rib's “vertical” deflection.There is also disclosed that the rolling rib 142 could well provide animproved method to rotate the frame 44 assemblies (a curved rack andpinion gear were shown in FIG. 22 of the 2^(nd) patent application (Ser.No. 12/587,043) and discussions of how this drive mechanism can separatethe torque effects such that each frame 44 is only subject to the torquefrom its own mirrors is discussed in paragraph 0088 of patentapplication serial number 12/587,043).

The present invention reveals a much more detailed analysis of exactlyhow the frame 44 system performs, and why, in terms of optical accuracy(as measured by slope error RMS—the key criteria customers provide todefine the optical accuracy). While WES's 2^(nd) patent applicationdetailed the support that the rolling rib 142 and associated rollerassemblies provided to the system, and discussed the concept of drivingthe frame's rotation via the rolling rib 142, the current inventionexpands and reveals the output of the analytical work explaining whicheffects (minimizing deflection or minimizing applied torque to theframes) have the greatest impact on the optical accuracy.

The slope error is more closely tied to the mirror deflections and thetorque effects of the entire frame 44; it is believed that the collectortubes “follow” the frame 44 in vertical deflection, minimizing anypositive effects from limiting vertical deflection.

When looking at the 7t7b Series 5 12 meter standard design, with 1, 2,3, 4 and 5 frames on either side of the drive, it is evident that theaverage slope error degrades from 1.910 for the case of only one frame44 on either side of the drive to 2.783 for the case with 5 frames oneither side of the drive. This clearly demonstrates that the appliedtorque of one frame 44 being turned by the drive and that frame 44 inturn driving a 2^(nd) (or even more) other frame(s) is what has thelargest effect on the slope error.

When looking at the worst case for the 7t7b Series 5 12 meter standardframe @ the periphery of the field, the effect of this applied torque onthe slope error is accentuated: 2.969 for a single frame on either sideof the drive to 4.801 with 5 frames on either side of the drive (theframe nearest the drive thus subject to the torque that the wind andweight cause for itself PLUS the applied additive torque from the other4 frames).

The one-sided rolling rib 142 and two-sided rolling rib 142 resultsfurther show that the rib location at the center does reduce the slopeerror to 1.744—vs.—having a rolling rib 142 at either end of the frame44 (two-sided rolling rib 142 of 1.790); the minor difference of 2.6%may be attributed to the support that the center rolling rib 142 adds tothe deflection resistance. The difference from the 1.790 and 1.828 isattributed to the difference between the rolling rib 142 turning anentire 12 meter frame 44—vs.—a two-sided rolling rib 142 with eachrolling rib 142 only turning ½ of the frame 44.

The connection of FIGS. 66 a and 66 b shows the beam 36, via the beamend piece 34, attached to the fin 90 of a node 10, such as Node C 122 orNode D 124 of the solar frame 44. The beam end piece strut legs 144 areattached to the beam 36 with fasteners 72. The beam end piece node fins146 are attached to the fin 90 of the node 10. Each of these componentsmust carry the axial and shear forces from the frame 44, the mirror deadloads and wind loads (on the face or back of the mirror), which causethis connection to have shear as well as axial forces (most struts 32 inthe space frame design have primarily axial forces, except for their ownweight, which causes minimal shear and bending moments).

The connection of FIGS. 67 a, 67 b, 67 c and 67 d shows the diagonalbeam 110 where the bottom of the beam 110 attaches with a pin 56 to thetop fin of Nodes A and B via bracketry. It also shows how an angledstrut 32 via its strut end piece 30 attaches to the top fin of the node148/beam 110 bracket 150. The fin 90, bracket 150 and beam 36 must carrythe axial and shear forces from the frame 44 and any moments, from themirror dead loads and wind loads (on the face or back of the mirror),which cause this connection to have shear as well as axial forces andmoments (most struts 32 in the space frame 44 design have primarilyaxial forces, except for their own weight, which causes minimal shearand bending moments).

Collector tube upright 152 is connected to a collector tube base 154through a top bracket 156 attached by fastener 72. The collector tubebase 154 is also connected to horizontal beam 108 with a bottom bracket158 through fastener 72, as shown in FIGS. 68A-C. The collector tubebracket 160 is attached to collector tube upright 152, as shown in FIG.68C.

The mirror rail 48 is connected to mirror bracket 162 with fasteners 72,as shown in FIGS. 69A, 69B and 69C.

The mirror rail 48 is connected to upper bracket 164, which is connectedto lower bracket 166, which is in turn connected to beam 36 connection,as shown in FIGS. 70A-70D. FIG. 70D shows a two piece rail mirror 58 tobeam 36 connection.

Pin 56 and Clip Designs

The fasteners 72 used to join the various chords 28, chord end pieces26, struts 32, strut end pieces 30, beams 36, beam end pieces 34, nodes,etc. can be pins 56, rivets, bolts, huck fasteners (Alcoa) or othermeans. FIGS. 71A, 71B, 72A, 72B and 73A, 73B and 73C show threaded pins168, where the pins can have a very slight clearance (on the order of0.001-0.002″ clearance to the mating holes) or be an interference fit.

During the insertion of the pins 168 for factory or field assembly ofthe various parts, tight fits are desirable. However, this can causedifficulty in assembly and possible galling, either of which can causeslower than desired assembly or damage to parts, which may be a currentor future problem. The use of pins 168 with a slight clearance or theuse of lubricant threads 170 can help to alleviate this.

The threads 170 or groove 200 are used for end retention (e.g. where eclips, nuts, lock nuts are used (cotter pins or other end retentiondevices are also possible). Threads 170 enable the closely fit pin tocarry some minor amount of lubricant to assist in the installation.Without these threads 170, any applied lubricant (wax, oil, boron, etc.)is in effect “squeegee'd” off during the insertion process in the firsttight hole (either due to an interference fit design or tolerance issues“crowding” the holes such that one edge may be tight to the fastener 72.The lubricant can be a wax, oil or other lubricant, and can be appliedeither prior to the field assembly or during the field assembly. Ineither case, if applied prior, at the time of fastener fabrication forexample, the application can be done by dipping the pin in the oil, waxor other lubricant, or by dripping, spraying, wiping, drum feeding or byother means of transferring lubricant onto the pin 168. By having thethreaded portion of the pin shaft, minor amounts of lubricant can be“carried” in the thread 170, ensuring that there is some lubricantavailable for subsequent hole insertion (these pins go through 2, 3 ormore fabricated surfaces). Because many of the components are thinwalled, having this lubricant available eases insertion and dramaticallyreduces the likelihood of galling during insertion, which can lead toinstallation difficulties, part deformation or even failure (thedeformation can induce local stresses and buckling, which may not evenbe known until the product is in use, leading to a potential futurefailure of unknown cause). A self-locking retaining ring/clip 174, asshown in FIG. 71A, or an E-style side mount retaining ring/clip 172, asshown in FIG. 71B, may be used with the pin 168 to fix the pin 168 inplace by engagement into retaining ring groove 200, as shown in FIGS.72A and 72B.

There are many other types of fasteners 72, pins 168, etc. that can beused to join these types of assemblies, including Alcoa/Huck fastenersand products like the SLIC Pins (see following info):

The Self Locking Implanted Cotter Pin 176, shown in FIG. 74 , is likehaving a pin and cotter all in one.

Strong spring-loaded plunger features easy insertion ramp and thevertical face at rear prevents backing out. This design is ideal forblind holes or where cotter pin access is limited.

The SLIC Pin™ eliminates cotters, bolts and nuts and does not requiretools for use—thereby greatly speeding assembly times. It is well suitedfor automated assembly and is easier, safer and faster.

Hybrid Solid Node with Hollow Fin(s):

The “Hybrid Solid. Node with Hollow Fin(s) 12” will be called the“hybrid node” to simplify this write-up (alternatively called the “solidnode hollow fin” in some figures). The hybrid node 86 utilizes a solidcentral portion 132 with at least one hollow fin 12. The hybrid node 86builds upon designs disclosed in WES's 1-4^(th) patent applications,most notably the strut end piece 30 to single fin 90 design shown in thefirst patent application (FIG. 84 ), the guided insertion single fin(FIG. 27A) and “knuckle” hollow fin 12 (FIG. 85 ) shown in the thirdpatent application and, of course, the solid node 92 described in the4^(th) patent application.

Supporting figures for the hybrid node 86 include FIGS. 75,76, 77, 78 &79 showing a more conventional solid node 92, while FIGS. 80, 81, 82 and83 show a hybrid node 86 design and Table 4 shows comparative results.FIG. 84 shows a strut end piece 30 to node single fin 90 from the 1^(st)patent application. FIG. 27A shows a guided insertion style hollow nodewith solid fins 90 from the 3^(rd) patent application and FIG. 85 showsa “knuckle” hollow fin 12 design also from the 3^(rd) patentapplication.

As disclosed in prior patent applications, one key attribute of thesolid node is that the solid central portion 132 undergoes very littledeformation during axial loading of the fins 90 (four fins are picturesin FIGS. 75-83 ). In prior designs with a hollow node 68 (FIGS. 84, 27Aand 85 , for example) as axial loads are placed onto the node fins, thecentral hollow portion (channel 206) of the node can be deformed(visualize a soda can where the wall of the can is pushed in or pulledoutward). For the solid node designs, this solid central portion 132,and while there is of course deformation from the axial loads on thenode fins, the deformation is much less than on the hollow node designs(reference the 4^(th) patent application).

FIG. 75 shows the cross sectional profile of a conventional solid node92 while FIG. 77 shows this node in isometric view. Axial and shearloading is depicted in FIG. 76 , shown on the solid node 92 (identicalloadings are applied to the hybrid node 86); please note that the nodesdepicted in this portion of the patent application are utilized withboth chords 28 and struts 32, which generally undergo axial loading, andwith beams 36, which undergo a combination of axial loads andwind/mirror weight loadings which translate into loads at a right angleto the axial loads which then result in side (—vs—axial) loading of thenode fins. Note that the chord loads of 829.8 lbs and 860.1 lbs and thestrut load of 50.4 lbs are true “axial loads” while the combined loadsof 0.9/249.5/589.3 lbs and 32.8/315.3/700.1 lbs on the two top finsrepresent the more complex, not-just-axial loads from the beamconnections. Please note that this node design is used in otherapplications, and that the partially hidden fin has an axial tensileload of 282.17 lbs applied to it (nor are the two holes on the top/beamfins depicted with a circle/line through circle).

The resulting deformation is depicted in FIG. 78 and the resultingequivalent stress is shown in FIG. 79 .

A similar node design with identical loadings, but utilizing the hybridnode 86 concept, is shown for this configuration of solid node bututilizing hollow—vs—solid fins. FIGS. 80-83 depict the profile crosssectional view, isometric views and resulting deformation and equivalentstress results respectively.

Table 4 shows how the conventional solid node 92 and hybrid nodes 86compare in this application. The hybrid node is ever so slightly greaterin circle size (5.08—vs—5.04″) and weighs 4.355 lbs/ft-vs-the solid nodeweight of 3.798 lbs/ft (14.7% heavier). The maximum deformation of thehybrid node is only 0.004″—vs—the solid node deformation of 0.010″ (dueto the side loading of the beam connections as discussed earlier) andthe maximum equivalent stress is very similar (10.31 ksi for the solidnode—vs—10.94 ksi for the hybrid node).

The hybrid node 86 design more ideally handles the “side” loads(depicted as 249.5 lbs and 315.3 lbs in FIG. 76 ). The solid node 92relies on the narrowest dimension (fin base 78) where the guidedinsertion fin 90 meets the node solid central portion 132 (shown as0.309″ in FIG. 75 ), while in FIG. 80 the hybrid node utilizes a hollowfin mating with the solid central portion of the node with a 1.0″dimension, providing greatly improved resistance to side loading. Notethat the fins of the hybrid node are depicted using parallel outsidesurfaces (for example, near the 0.212″ dimension) while the fin tips 80provide the “guided insertion” functionality discussed in the 3^(rd)patent application. These outside walls (first leg 178, second leg 180and third leg (top) 182) could easily be slightly bowed to provide asimilar overall “guided insertion” design feature, but for simplicitiessake, this was not shown on the profile cross sectional design for thehybrid node because it would complicate the design with additionaldimensions required.

As shown in FIGS. 80 and 81 , the cross sectional profile design for thehybrid 86 design utilized two different means to connect the hollow finsto the solid central portion 132. Looking at the cross section, the fins90 can be described as being in the 3:00, 5:00, 7:00 and 10:00positions. For the 3:00 position, the outside surfaces (178 and 180) ofthe hollow fin connect directly to the side of the solid centralportion. The 5:00 fin shows the upper right outside surface connectingto the bottom outside surface of the 3:00 fin, with the lower leftoutside surface of the 5:00 fin connection more directly to the bottomof the solid central portion of the node. The 7:00 fin connectssimilarly to the 10:00 fin's bottom outside surface (and then through ashort section of material to the solid central portion of the node) andto the solid central portion of the node. The 10:00 fin connectssimilarly to the 7:00 fin's top outside surface (and then through ashort section of material to the solid central portion of the node) withthe top outside surface of the 10:00 fin connecting more directly to thesolid central portion of the node.

When designing the extrusion profile and cross sectional dimensions, itis necessary to take into account the Aluminum Design Manual (2010)(ADM) technical rules regarding part design (safety factors, etc.) whichfor a part such as those shown include possible failure modes of tensionthrough net section area, block shear failure, and bearing stressfailures as well as hole-to-edge distance requirements. Loadingcalculations for mating parts are performed utilizing the appropriatefasteners, and the final design is often a tradeoff between materialchoices for the extrusions and the fasteners, fastener (and thus hole)diameters and profile cross sections (width and thicknesses). Inaddition to these requirements of the ADM, profile designs, materialchoice and geometry/loading cases are evaluated using Finite ElementAnalysis to predict the resulting area deflections and equivalentstresses throughout the part. When reviewing the hybrid node 86 design,for example, the loading can be seen in FIG. 76 (the same loadingvectors are used for the solid fin 90 and hybrid node designs) with FIG.82 showing the deformation and FIG. 83 showing the equivalent stress.

It is evident from the resulting deformation and equivalent stress FIGS.(82 and 83) that the cross sectional profile design handles the loadingcases whether the connection of the outside surface (178 and 180) of thehollow fin is directly to the solid central portion 132 of the node orwhether it is via the outside surface of another fin and then to thenode.

In summary, the hybrid node 86 allows for greatly improved deformationresults from side loading with only a minor increase in part weight.

TABLE 4 LBS MAX MAX. CIRCLE PER DEF EQUIV DESCRIPTION SIZE (94) FT (IN)STRESS SOLID NODE 4.815 3.798 0.010 10.31 SOLID FIN (214) SOLID NODE4.85 4.355 0.004 10.94 HOLLOW FIN (212)

Table 4 above shows the circle, size, lbs/ft and resulting maximumdeflection and equivalent stress for solid node/solid fin 92 and solidnode/hollow fin (hybrid) 86 designs as shown in FIGS. 75 through 83 .These design concepts could be utilized for other loading and geometrycases besides the specific cases shown, and the resulting conceptualdesigns of the solid node/solid fin and solid node/hollow fin extrusionscould thus handle increased loads of 750 lbs normal to the profile's“fins” 90 and 1300 lbs along the axis of the fins with 2,000 lbs axialforce along the chord 28 axis, with corresponding changes to extrusioncircle size 94 of less than 12″, less than 12 lbs/ft extrusion weightand maximum deflections of less than 0.100″ and maximum equivalentstress of less than 21 ksi.

Although the invention has been described in detail in the foregoingembodiments for the purpose of illustration, it is to be understood thatsuch detail is solely for that purpose and that variations can be madetherein by those skilled in the art without departing from the spiritand scope of the invention except as it may be described by thefollowing claims.

The invention claimed is:
 1. A method for producing a node for a solarmirror support frame comprising the step of: placing an aluminum billethaving a diameter of less than 13 inches into a die; and extruding thebillet through the die so an extrusion is formed having an elongateportion to which a structural element is attached, and a fin extendingradially outward from the elongate portion where at least 5% of thevolume of the fin is replaced by at least a single void extending inparallel with the elongate portion, the fin having a free end, theelongate portion and the fin having a circle diameter of less than 12inches, the fin supporting at least 200 lbs of load, the elongateportion and fin being one continuous piece of aluminum, the elongateportion has a closed shape; cutting the extrusion to form the node; andfabricating the node to produce a fastener hole in the fin.
 2. Themethod as described in claim 1 wherein the fin has a first leg andextends outward from the elongate portion, and a second leg that extendsoutward from the elongate portion and adjacent to the first leg with thevoid disposed between the first and second legs.
 3. The method asdescribed in claim 2 wherein the fin has a third leg that is connectedto the first and second legs and the first leg is in spaced relationwith the second leg.
 4. The method as described in claim 3 wherein thefirst, second and third legs form a rectangular cross-section.
 5. Themethod as described in claim 4 wherein the first leg has a hole and thesecond leg has a hole which aligns with the hole of the first leg andthrough which a fastener extends to fasten a strut end piece to the fin.6. The method as described in claim 5 wherein the fin has a notch at itsends to avoid interference with the strut end piece.